Ophthalmology Flashcards
what is dry macular degeneration characterised by?
• Dry macular degeneration: characterized by Drusen - yellow round spots in Bruch’s membrane
what is wet macular degeneration characterised by?
Wet (exudative, neovascular) macular degeneration: characterized by choroidal
neovascularisation. Leakage of serous fluid and blood can subsequently result in a rapid loss of vision. Carries worst prognosis
how is macular degeneration classified?
• Early age related macular degeneration (non-exudative, age related maculopathy): drusen and
alterations to the retinal pigment epithelium (RPE)
• Late age related macular degeneration (neovascularisation, exudative)
what are risk factors for macular degeneration?
- Age: most patients are over 60 years of age
- Family history
- Smoking
- More common in caucasians
- ♀sex
- High cumulative sunlight exposure
what are features of macular degeneration?
- ↓ visual acuity: ‘blurred’, ‘distorted’ vision, central vision is affected first
- Central scotomas
- Fundoscopy: drusen, pigmentary changes
what is included in the general management of macular degeneration?
• Stopping smoking
• High does of β-carotene, vitamins C and E, and zinc may
help to slow down visual loss for patients with established macular degeneration. Should avoid smoking due to an ↑ risk of lung cancer
what is the management of wet macular degeneration?
- Photocoagulation
- Photodynamic therapy
- anti-vascular endothelial growth factor (anti-VEGF) treatments: intravitreal ranibizumab
what are 5 causes of sudden painless loss of vision?
- Ischemic optic neuropathy (e.g. Temporal arteritis or atherosclerosis)
- Occlusion of central retinal vein
- Occlusion of central retinal artery
- Vitreous hemorrhage
- Retinal detachment
describe the clinical features of amaurosis fugax?
Amaurosis fugax: classically described as a transient monocular vision loss that appears as a “curtain coming down vertically into the field of vision in one eye”. Sometimes it occurs as episodes, caused by ipsilateral carotid artery diease.
Ischaemic optic neuropathy:
- what is this caused by?
- what is the pathophysiology?
- what visual defect is seen?
- what is seen at fundoscopy?
- May be due to arteritis (e.g. Temporal arteritis) or atherosclerosis (e.g. HTN, DM, old patient)
- Due to occlusion of the short posterior ciliary arteries, causing damage to the optic nerve
- Altitudinal field defects are seen → loss of vision above or below the horizontal level
Central retinal vein occlusion:
- how does age affect incidence?
- what are the causes?
- what is seen at fundoscopy?
- Incidence ↑ with age, more common than arterial occlusion
- Causes: glaucoma, polycythemia, hypertension
Fundoscopy
• Widespread retinal haemorrhages in all 4 quadrants, which vary in appearance from a small-scattered retinal hemorrhages to marked confluent hemorrhages
• Marked dilated and tortuous retinal vessels
• Cotton-wool spots
• Optic disc edema, macular edema, and retinal
thickening
• Vitreous hemorrhages may be present
Central retinal artery occlusion:
- causes
- clinical features
- fundoscopy findings
- Due to thromboembolism (from atherosclerosis) or arteritis (e.g. Temporal arteritis)
- Features include Afferent pupillary defect, ‘cherry red’ spot on a pale retina
- Diffuse edema makes the retina and arteries look pale. Perfused underlying tissues show through the thin fovea giving a classic cherry-red spot appearance
Vitreous haemorrhage:
- causes
- features
- points on history
• Causes: diabetes, bleeding disorders
• Features may include sudden visual loss,
dark spots
• Large bleeds cause sudden visual loss
• Moderate bleeds may be described as numerous dark spots
• Small bleeds may cause floaters
what are the clinical features seen in posterior vitreous detachment?
- Flashes of light (photopsia) - in the peripheral field of vision
- Floaters, often on the temporal side of the central vision
what clinical features are seen in retinal detachment?
- Dense shadow that starts peripherally progresses towards the central vision
- A veil or curtain over the field of vision
- Straight lines appear curved (positive Amsler grid test)
- Central visual loss
where is the lesion in a relative afferent pupillary defect?
Relative afferent pupillary defect: Also known as the Marcus-Gunn pupil, a relative afferent pupillary defect is found by the ‘swinging light test’. It is caused by a lesion anterior to the optic chiasm i.e. optic nerve or retina
what are two causes of RAPD?
Causes
• Retina: detachment
• Optic nerve: optic neuritis e.g. Multiple sclerosis
describe the afferent and efferent pathways of the pupillary light reflex
Pathway of pupillary light reflex
• Afferent: retina → optic nerve → lateral geniculate body → midbrain
• Efferent: edinger-westphal nucleus (midbrain) → oculomotor nerve
- Third nerve palsy
- Holmes-adie pupil
- Traumatic iridoplegia
- Pheochromocytoma
- Congenital
All cause what kind of pupil?
mydriasis: large pupil
what are drug causes of mydriasis?
Drug causes of mydriasis
• Topical mydriatics: tropicamide, atropine
• Sympathomimetic drugs: amphetamines
• Anticholinergic drugs: tricyclic antidepressants
who is holmes-adie pupil seen in? what kind of pupil is seen?
Holmes-ADIe pupil is a benign condition most commonly seen in women. It is one of the differentials of a DIlated pupil
Holmes-adie pupil:
- is this bilateral or unilateral?
- what happens once the pupil has constricted?
- is this reactive to accomodation? to light?
• Unilateral in 80% of cases
• Dilated pupil
• Once the pupil has constricted it remains small for an
abnormally long time
• Slowly reactive to accommodation but very poorly (if at all) to light
The absence of which reflexes are associated with holmes adie pupil - called holmes adie syndrome?
Holmes-Adie syndrome
• Association of Holmes-Adie pupil with absent ankle/knee reflexes
what is angioid retinal streaks on fundoscopy?
Angioid retinal streaks are seen on fundoscopy as irregular dark red streaks radiating from
the optic nerve head. The elastic layer of Bruch’s membrane is characteristically thickened and calcified